1. Field of the Invention
The present invention relates to a navigational aid or nautical instrument, and more particularly, pertains to a rate of turn indicator for indicating the rate of turn from a course of travel for a vessel or other like vehicle.
2. Description of the Prior Art
One of the most critical problems confronting the shipping industry, particularly towboats, is steering a vessel on a straight and true course without swinging or turning from the predetermined course due to forces of nature such as winds, tides, waves, etc.
The prior art gyros also contain many points of mechanical friction which make them difficult or impossible to respond to very low rates of turn and to properly return to zero.
Prior art gyroscopic instruments have been very expensive. The prior art gyros are usually complex, expensive, electromechanical instruments with numerous mechanical components subject to structural failure, in addition to electrical failure. The prior art instruments have included components such as gears, springs, rotors and brushes, centrifugal switches, all of which are subject to failure. Finally, the instruments have circuitry which sparks and can be hazardous in explosive environments. In any event, if the instruments are purchased, after a costly financial outlay by an operator, the installation, subsequent maintenance, and repair are expensive.
U.S. Pat. No. 4,316,389, incorporated herein by reference, teaches a novel rate of turn indicator which overcomes many of the disadvantages of the prior art. However, this reference teaches a system wherein the gyro wheel and the drive motor are fixedly attached by mechanical means. Unfortunately, this tends to provide a system which may be subject to mechanical shock in certain environments.
The present invention overcomes the disadvantages of prior art by providing a rate of turn indicator having easy visual readout for a steersman of a vessel that a rate of turn or swing is occurring, and yet sensitive and accurate to the rate of turn while eliminating prior art problems due to friction between components. A magnetic drive replaces direct gyro drive systems, thus eliminating and alleviating rotating member fatigue at the hub of the gyro.